1
27-x³=(3-x)(9+3x+x²)
x³-64xy²=x(x²-64y²)=x(x-8y)(x+8y)
3a²-18a+27=3(a²-6a+9)=3(a-3)²
2ab+10b-2a-10=2b(a+5)-2(a+5)=(a+5)(2b-2)
2
=8a³-1=8*(-1/64)-1=-1 1/8
3
a²-b²+a-b=(a-b)(a+b)+(a-b)=(a-b)(a+b+1)
=x+y+b(x+y)=(x+y)(1+b)
=(2x-y)²-9=(2x-y-3)(2x-y+3)
=(5y+1)²
=(x^5-3b)²
4
12x(x²-4)=0
x=0
x²-4=0⇒x²=4⇒x=2 U x=-2
2x(25x²-10x+1)=0
2x(5x-1)²=0
x=0
5x-1=0⇒x=1/5
(x-7)(x+7)=0
x=7 U x=-7
(5y-2)(5y+2)=0
y=0,4 U y=-0,4
5
[(2^4)³+5³]/21=(16+5)(16²-16*5+5²)/21=16²-16*5+5²